Wafer processing system using multi-zone chuck

ABSTRACT

A wafer processing system includes at least one metrology chamber, a process chamber, and a controller. The at least one metrology chamber is configured to measure a thickness of a first layer on a back side of a wafer. The process chamber is configured to perform a treatment on a front side of the wafer. The front side is opposite the back side. The process chamber includes therein a multi-zone chuck. The multi-zone chuck is configured to support the back side of the wafer. The multi-zone chuck has a plurality of zones with controllable clamping forces for securing the wafer to the multi-zone chuck. The controller is coupled to the metrology chamber and the multi-zone chuck. The controller is configured to control the clamping forces in the corresponding zones in accordance with measured values of the thickness of the first layer in the corresponding zones.

PRIORITY CLAIM

The present application is a divisional of U.S. application Ser. No.13/338,885, filed Dec. 28, 2011, which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The present disclosure relates to wafer processing systems usingmulti-zone chucks.

BACKGROUND

A recent tendency in the field of semiconductor manufacturing is toreduce production costs by using larger wafers. The migration to alarger wafer size, while rewarding in an increased number of chips perwafer, also poses numerous technical challenges, such as maintenance ofa uniform processing environment across a large wafer.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments are illustrated by way of example, and not bylimitation, in the figures of the accompanying drawings, whereinelements having the same reference numeral designations represent likeelements throughout. The drawings are not to scale, unless otherwisedisclosed.

FIG. 1 is a schematic view of a wafer processing system in accordancewith some embodiments.

FIG. 2 is a schematic cross-section view of an electrostatic chuck inaccordance with some embodiments.

FIG. 3A is a schematic top view of a multi-zone chuck in accordance withsome embodiments.

FIG. 3B is a schematic cross-section view of the multi-zone chuck ofFIG. 3A.

FIGS. 3C and 3D are schematic top views of multi-zone chucks inaccordance with some embodiments.

FIG. 4 is a block diagram of a wafer processing system in accordancewith some embodiments.

FIGS. 5-6 are flow charts of various methods in accordance with someembodiments.

FIG. 7 is a block diagram of a computer system in accordance with someembodiments.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments or examples, for implementing different featuresof various embodiments. Specific examples of components and arrangementsare described below to simplify the present disclosure. An inventiveconcept may, however, be embodied in many different forms and should notbe construed as being limited to the embodiments set forth herein;rather, these embodiments are provided so that this description will bethorough and complete, and will fully convey an inventive concept tothose of ordinary skill in the art. It will be apparent, however, thatone or more embodiments may be practiced without these specific details.

In the drawings, the thickness and width of layers and regions areexaggerated for clarity. Like reference numerals in the drawings denotelike elements. The elements and regions illustrated in the figures areschematic in nature, and thus relative sizes or intervals illustrated inthe figures are not intended to limit the scope of an inventive concept.

FIG. 1 is a schematic view of a wafer processing system 100 inaccordance with some embodiments. The wafer processing system 100 inFIG. 1 includes a load lock chamber 110, a plurality of process chambers120, a robot 130, a controller 140, and one or more metrology chambers150. The load lock chamber 110 transfers wafers into and out of thewafer processing system 100, e.g., under a vacuum environment. The robot130 transfers the wafer among the load lock chamber 110, the processchambers 120, and the metrology chambers 150. The process chambers 120are equipped to perform numerous processes or treatments, such asChemical Vapor Deposition (CVD), Atomic Layer Deposition (ALD), PhysicalVapor Deposition (PVD), annealing, etching, degassing, pre-cleaning,cleaning, post-cleaning, etc. The metrology chambers 150 are configuredto measure various properties of wafers before, during or afterprocessing. In some embodiments, one or more metrology chambers 150is/are integrated in one or more of the process chambers 120. Thecontroller 140 is configured to control wafer measurement, transfer andprocessing. In one or more embodiments, the controller 140 comprises ahardware platform, such as a processor or controller chip coupled with amemory, which is programmable by software and/or firmware to perform thefunctions described herein. In some embodiments, the controller 140comprises a dedicated hardware circuit, e.g., in the form of anapplication-specific integrated circuit (ASIC) hardwired to perform oneor more of the processes described herein. While five process chambers120 and two metrology chambers 150 are shown, other numbers of processchambers 120 and/or metrology chambers 150 are within the scope of thisdisclosure. Likewise, in some embodiments, more than one robot 130and/or load lock chamber 110 are included in the processing system 100.

One or more of the process chambers 120 includes therein a chuck forsupporting a wafer while a treatment is being performed on the wafer inthe process chamber 120. In some embodiments, the chuck is anelectrostatic chuck that uses the attraction of opposite charges on thechuck and on a wafer supported by the chuck to hold or secure the waferon the chuck. In some embodiments, the chuck is a vacuum chuck thatgenerates vacuum pressures through a number of vacuum ports in the chuckto hold the wafer on the chuck.

FIG. 2 is a schematic cross-section view of an electrostatic chuck 200in accordance with some embodiments for securing thereon a wafer 260.The wafer 260 has a front side 268 and an opposite, back side 267 bywhich the wafer 260 is supported on the electrostatic chuck 200. Theelectrostatic chuck 200 includes a chuck plate 210, a base 220, avoltage controller 230, a heat transfer gas source 240, and one or moreheaters 250. In some embodiments, lifting pins are included to lift thewafer 260 off the chuck plate 210, and to lower the wafer 260 onto thechuck plate 210.

The chuck plate 210 includes electrodes 212, 214 embedded in adielectric body 216. The dielectric body 216 defines a supportingsurface 217 on which the wafer 260 is to be supported. The dielectricbody 216 defines an insulator for the electrodes 212, 214 embeddedtherein.

The electrodes 212, 214 are coupled to the voltage controller 230 in abipolar arrangement. In some embodiments, one of the electrodes 212, 214is omitted to form a monopolar arrangement. In a monopolar arrangement,a voltage is applied from the voltage controller 230 to the electrode,e.g., 212, and causes electrostatic charges, e.g., negative charges, 213to accumulate near the electrode 212. Electrostatic charges of theopposite polarity, e.g., positive charges, 263 accumulate in the wafer260 on or near the back side 267 by which the wafer 260 is supported onthe supporting surface 217 of the chuck plate 210. A clamping force F(also referred to as gripping force or pressure) is cause by theelectrostatic attraction between the accumulated charges having oppositepolarities, to hold or secure the wafer 260 on the chuck plate 210.

In a bipolar arrangement, different voltages VA, VB are applied to apair of electrodes, e.g., the electrodes 212, 214. For example, thevoltage VA applied to the electrode 212 causes negative charges 213 toaccumulate near the electrode 212, whereas the voltage VB applied to theelectrode 214 causes positive charges 215 to accumulate near theelectrode 214. An electrode-wafer voltage V is half of the voltagebetween the electrodes 212, 214. Where VA is a negative voltage and VBis a positive voltage, V=(−VA+VB)/2. Electrostatic charges of oppositepolarities, e.g., positive charges 263 and negative charges 265,accumulate in the wafer 260 on or near the back side 267. A clampingforce F is caused by the electrostatic attraction between theaccumulated charges having opposite polarities, to hold or secure thewafer 260 on the chuck plate 210.

The clamping force F depends on a variety of factors, including the sizeg of the gap 290, the thickness d of the dielectric body 216 between theelectrodes 212, 214 and the supporting surface 217, the electrode-wafervoltage V applied to the electrodes 212, 214, the electric constantκ_(r) of the dielectric body 216, etc. Namely, the clamping force F isproportional to [∈_(o)/2][Vκ_(r)/{d+κ_(r)g}]², where ∈_(o)=8.85×10⁻¹².The size g of the gap 290 affects the clamping force F. For example,when the dielectric body 216 includes alumina with an electric constantκ_(r) of about 10, a gap size g of about 1/10 of the dielectricthickness d will decrease the clamping force F about 4 times.

The wafer 260 is heated by heat generated by the heaters 250 (e.g.,resistive heating elements) and transferred via the dielectric body 216and across gap 290 between the back side 267 of the wafer 260 and thesupporting surface 217 of the chuck plate 210. In one or moreembodiments, a heat transfer gas 295, e.g., helium, is supplied from theheat transfer gas source 240 to the gap 290 to improve heat transferbetween the electrostatic chuck 200 and the wafer 260.

A gap, such as 290, exists due to one or more properties on the backside of the wafer supported on a chuck, such as warpage of the wafer,the presence of contaminants, or a varying thickness of a layer on theback side of the wafer, etc. Such properties reflect a non-uniformity onthe back side of the wafer. The non-uniformity on the back side of thewafer results in different gap sizes in different areas of the waferwith respect to the chuck which, in turn, result in non-uniformity inheat transfer from one or more heater in the chuck to the wafersupported thereon. Such a non-uniform heat transfer exists whether avacuum chuck or an electrostatic chuck is used. The non-uniform heattransfer further affects one or more other property of the wafer, e.g.,uniformity of a thickness of a layer deposited on the front side of thewafer while the wafer is being secured by its back side on the chuck.

In some embodiments, by controlling the clamping forces in multiplezones of the chuck to compensate for a non-uniformity on the back sideof the wafer, the wafer is brought into a uniform thermal conductivitywith the chuck. Thus, a uniform heat transfer between the chuck and thewafer is achievable. For this purpose, the chuck includes multiple zoneswith controllable clamping forces. Such a chuck is referred to herein asa multi-zone chuck which is an electrostatic chuck in some embodimentsor a vacuum chuck in further embodiments.

FIG. 3A is a schematic top view of a multi-zone chuck 300 in accordancewith some embodiments, and FIG. 3B is a schematic cross-section view ofthe multi-zone chuck 300 of FIG. 3A. The multi-zone chuck 300 includes aplurality of zones Z1, Z2, . . . Zn with corresponding clamping forcesF1, F2, . . . Fn. In one or more embodiments, the clamping force in atleast one of the zones is controllable independent of the clamping forcein at least another one of the zones. For example, at least the clampingforce F1 in the zone Z1 is controllable independent of the clampingforce F2 in the zone Z2. In some embodiments, the clamping forces ineach of the zones is controllable independent of the clamping forces inthe other zones. For example, the clamping forces F1, F2, . . . Fn areall controllable independent of each other.

The physical arrangement and/or shape and/or number of the zones Z1, Z2,. . . Zn on the multi-zone chuck 300 is/are not limited to anyparticular specifics. For example, the zones Z1, Z2, . . . Zn in FIG. 3Aare configured in a ring form in which each zone is one among aplurality of concentric rings. In another example, the zones Z1, Z2, . .. Zn in FIG. 3C are configured in a grid form in which each zone is oneamong a plurality of cells in a grid. In a further example, the zonesZ1, Z2, . . . Zn in FIG. 3D are configured in a mixed form in which eachzone is one among a plurality of segments of a ring among a plurality ofconcentric rings. The above described configurations are forillustrative purposes only and are non-limiting.

The multi-zone chuck 300 is an electrostatic chuck. The clamping forcesin the zones Z1, Z2, . . . Zn are controllable by providing separateelectrodes (in a monopolar arrangement) or different pairs of electrodes(in a bipolar arrangement) in different zones. Different voltages arethen applied to the electrodes or the pairs of electrodes in differentzones for varying the clamping forces of the zones. The bipolararrangement is illustrated in FIG. 3B and will be described hereinbelow. A similar description is applied to the monopolar arrangement.

In the bipolar arrangement of the multi-zone chuck 300 in FIG. 3B, eachzone includes a pair of electrodes. For example, the zone Z1 includes apair of electrodes 312, 314, the zone Z2 includes a pair of electrodes322, 324, . . . the zone Zn includes a pair of electrodes 3 n 2, 3 n 4.The pairs of electrodes are connected to a voltage controller 330 whichis configured to apply different voltages V1, V2, . . . Vn to thecorresponding pairs of electrodes. Each of the voltages V1, V2, . . .Vn, e.g., V1, corresponds to the electrode-wafer voltage V discussedwith respect to FIG. 2, and is half of the voltage between thecorresponding electrodes, e.g., 312, 314. By controlling the voltagesV1, V2, . . . Vn applied to the corresponding zones Z1, Z2, . . . Zn,the clamping forces F1, F2 . . . Fn generated in the zones Z1, Z2, . . .Zn are also controlled.

In embodiments where the multi-zone chuck is a vacuum chuck, each of thezones Z1, Z2, . . . Zn includes one or more vacuum ports to which acontrollable vacuum pressure is applied from vacuum source. Bycontrolling the vacuum pressures applied to the vacuum ports indifferent zones of the vacuum chuck, the clamping forces of the vacuumchuck in various zones thereof are controllable.

FIG. 4 is a block diagram of a wafer processing system 400 in accordancewith some embodiments. The wafer processing system 400 includes apre-treatment metrology chamber 450, a process chamber 420, a controller440, a storage device 480, and a post-treatment metrology chamber 456.The process chamber 420 includes a multi-zone chuck, such as themulti-zone chuck 300. The controller 440 includes a voltage controller,such as the voltage controller 330. In some embodiments, the voltagecontroller 330 is integrated in the multi-zone chuck 300 which iscoupled to the controller 440 to be controlled by the controller 440.The controller 440 is also coupled to the metrology chambers 450, 456,the process chamber 420, and the storage device 480 for controlling ordata exchange with the metrology chambers 450, 456, the process chamber420, and the storage device 480.

In some embodiments, the controller 440 includes several unitsdistributed among one or more of the process and metrology chambers ofthe wafer processing system 400. In some embodiments, one or more of thestorage device 480 and the further metrology chamber 456 is omitted. Insome embodiments, the metrology chamber 450 is configured to function asboth a pre-treatment metrology chamber and a post-treatment metrologychamber. In some embodiments, one or more of the process chamber 420,the metrology chambers 450, 456, and the controller 440 in the waferprocessing system 400 corresponds to one or more of the process chambers120, the metrology chambers 150, and the controller 140 in the waferprocessing system 100.

FIG. 5 is a flow chart of a wafer processing method 500 in accordancewith some embodiments. In one or more embodiments, the wafer processingmethod 500 is performed by the wafer processing system 400.

At step 505, the wafer 260 is placed inside the pre-treatment metrologychamber 450, and a first property on the back side 267 of the wafer 260is measured by an appropriate tool equipped in the pre-treatmentmetrology chamber 450. In some embodiments, the first property reflectsa non-uniformity on the back side 267 of the wafer 260 including, butnot limited to, warpage of the wafer 260, the presence and/or nature ofcontaminants on the back side 267 of the wafer 260, a varying thicknessof a layer on the back side 267 of the wafer 260, etc. In an example,the first property is a thickness of a first layer 465 on the back side267 of the wafer 260. The thickness of the first layer 465 isnon-uniform, i.e., is thicker in one or more regions, e.g., 467, than inone or more other regions, 466.

At step 510, the wafer 260 is transferred (e.g., by the robot 130described with respect to FIG. 1) to the process chamber 420. In theprocess chamber 420, the back side 267 of the wafer 260 is supported onthe multi-zone chuck 300 having a plurality of zones Z1, Z2, . . . Znwith controllable clamping forces F1, F2, . . . Fn.

The wafer 260 is then secured to the multi-zone chuck 300 by controllingthe clamping forces F1, F2, . . . Fn in the corresponding zones Z1, Z2,. . . Zn in accordance with measured values P1, P2, . . . Pn of thefirst property in the zones Z1, Z2, . . . Zn. The controlling operationis performed by the controller 440 which obtains the measured values P1,P2, . . . Pn of the first property in the zones Z1, Z2, . . . Zn fromthe pre-treatment metrology chamber 450. In some embodiments, thecontroller 440 reads a first pre-stored data set 482, e.g., a look-uptable (LUT), in the storage device 480. For each measured value of thefirst property in a zone, e.g., the measured value P1 in the zone Z1,the controller 440 extracts from the first pre-stored data set 482 acorresponding value for the corresponding clamping force F1. Based onthe extracted value for the corresponding clamping force F1, thecontroller 440 controls the voltage controller 330 to apply anappropriate voltage V1 to the corresponding electrodes in the zone Z1. Asimilar clamping force control process is performed for the other zonesof the multi-zone chuck 300. A set of voltages V1, V2 . . . Vn is thusobtained. In some embodiments, the obtained voltages V1, V2 . . . Vn arestored as voltage data 483 in the storage device 480 for subsequent useon other wafers in a wafer batch.

The first pre-stored data set 482 is determined in order to tune thecontrolled clamping forces F1, F2, . . . Fn toward a predeterminedtarget. In some embodiments, where the presence and/or nature ofcontaminants or the non-uniformity of the thickness of the layer 465 onthe back side 267 of the wafer 260 results in different gap sizes (indifferent zones of the multi-zone chuck 300) between the back side 267of the wafer 260 and the multi-zone chuck 300, the first pre-stored dataset 482 is determined in order to compensate for such non-uniformity,i.e., to obtain a substantially uniform gap size across the wafer. Toachieve this goal, for example, voltages applied by the voltagecontroller 330 to the zones where the layer 465 is thick are increasedcompared to voltages applied to the zones where the layer 465 is thin orabsent. Specifically, if the layer 465 is formed by a preceding spincoating, the zones along the edge of the wafer 260 are likely to have alower thickness of the layer 465, and as a result, lower voltages areapplied by the voltage controller 330 to the edge zones.

Another target, in accordance with in some embodiments, is a uniformheat transfer from the multi-zone chuck 300 to the wafer 260 during atreatment to be performed on the wafer 260 in the process chamber 420.Generally, a uniform gap size between the multi-zone chuck 300 and thewafer 260 results in a uniform heat transfer. However, if other factorsexist, e.g., the heat transfer is conducted better through zones wherethe layer 465 is thinner or absent, such factors are also taken intoaccount while developing the first pre-stored data set 482. In someembodiments, the first pre-stored data set 482 is developed by runningone or more tests with one or more test wafers, and collecting the testdata to develop the first pre-stored data set 482. In one or moreembodiments, the first pre-stored data set 482 is developed or updatedduring manufacture of device wafers. In some embodiments, the firstpre-stored data set 482 is presented by an equation, in addition to orin lieu of, the LUT.

In some embodiments, the controller 440 is configured to performAdvanced Process Control (APC). The control action of the controller 440in steps 505-510 is a feed-forward control to adjust the currenttreatment to be performed in the process chamber 420 in order tocompensate for a variability caused by an upstream treatment 419. Insome embodiments, the feed-forward control is wafer-to-wafer, orbatch-to-batch. In some embodiments, the controller 440 further includesa feed-back control to minimize a variability of the current treatmentin a subsequent run.

Specifically, after step 515 at which the current treatment is performedin the process chamber 420 on the wafer 260, subsequent steps 520, 525,530 constituting the feed-back control are performed. The treatmentperformed in the process chamber 420 includes, but is not limited to,deposition, e.g., by CVD, ALD, PVD, annealing, etching, degassing,pre-cleaning, cleaning, post-cleaning, etc.

At step 520, the wafer 260 is transferred (e.g., by the robot 130described with respect to FIG. 1) to the post-treatment metrologychamber 456 (or back to the pre-treatment metrology chamber 450 wherethe metrology chamber 450 is configured to perform as both apre-treatment and a post-treatment metrology chamber). In thepost-treatment metrology chamber 456, a second property of the wafer 260after the treatment in the process chamber 420 is measured. The secondproperty in this post-treatment measurement is different from the firstproperty in the pre-treatment measurement at step 505. In someembodiments, the second property is a critical dimension (CD) orthickness of a layer deposited, etched or patterned on the front side268 of the wafer 260. After the post-treatment measurement, the wafer260 is transferred to a downstream treatment 421.

At step 525, the controller 440 obtains the measured values Q1, Q2, . .. Qn of the second property in the zones Z1, Z2, . . . Zn from thepost-treatment metrology chamber 456, and adjusts the clamping forcesF1, F2, . . . Fn in the corresponding zones Z1, Z2, . . . Zn inaccordance with measured values Q1, Q2, . . . Qn of the second propertyin the zones Z1, Z2, . . . Zn. The adjustment is performed by thecontroller 440 reading a second pre-stored data set 484, e.g., a LUT, inthe storage device 480. For the measured value of the second property inone or more zone, e.g., the measured value Q1 in the zone Z1, thecontroller 440 extracts from the second pre-stored data set 484 acorresponding value for adjusting the corresponding clamping force F1.Based on the extracted value for adjusting the corresponding clampingforce F1, the controller 440 controls the voltage controller 330 toupdate an adjusted voltage V1 to the corresponding electrodes in thezone Z1. A similar clamping force adjustment process is performed forone or more of the other zones of the multi-zone chuck 300. An adjustedset of voltages V1, V2 . . . Vn is thus obtained.

The second pre-stored data set 484 is determined in order to tune thecontrolled clamping forces F1, F2, . . . Fn toward a predeterminedtarget. In some embodiments, the target is to minimize variability ofthe second property. For example, where the second property is athickness of a layer 469 deposited on the front side 268 of the wafer260, a variability (or non-uniformity) of the thickness of the depositedlayer 469 was likely caused by non-uniform heat transfer from themulti-zone chuck 300 to the wafer 260 during the deposition in theprocess chamber 420. Specifically, an increased thickness of thedeposited layer 469 in a particular zone, e.g., Z1, indicates that theheat transfer from the multi-zone chuck 300 to the wafer 260 in the zoneZ1 during the deposition was excessive. Such an excessive heat transferwas likely caused by a too strong clamping force F1 in the zone Z1. Thecorresponding voltage V1 in the stored voltage data 483 is reduced inaccordance with a corresponding value extracted by the controller 440from the second pre-stored data set 484. Similarly, in a zone with areduced or no thickness of the deposited layer 469, the correspondingvoltage in the stored voltage data 483 is increased. In someembodiments, not every voltage in the voltage data 483 is adjusted.

In some embodiments, the second pre-stored data set 484 is developed byrunning one or more tests with one or more test wafers. In one or moreembodiments, the second pre-stored data set 484 is developed or updatedduring manufacture of device wafers. In some embodiments, the secondpre-stored data set 484 is presented by an equation, in addition to orin lieu of, the LUT.

The voltage data 483 after the adjustment at step 525 includes anadjusted set of voltages. At step 530, the adjusted set of voltagesrepresents adjusted clamping forces to be generated by the multi-zonechuck 300 for securing a subsequent wafer during a subsequent run of thetreatment in the process chamber 420.

FIG. 6 is a flow chart of a wafer processing method 600 in accordancewith some embodiments. In one or more embodiments, the wafer processingmethod 600 is performed by the wafer processing system 400.

At step 603, warpage of a wafer 260 is measured. In some embodiments,the wafer warpage is measured in the pre-treatment metrology chamber 450or a different metrology chamber. For example, a laser is scanned on thefront side 268 of the wafer 260 to measure the height of the front side268 at a plurality of points or zones. Based on the measurement, adegree and/or a direction of the wafer warpage is/are determined.

At step 605, a thickness of the layer 465 on the back side 267 of thewafer 260 is measured, in the pre-treatment metrology chamber 450 asdiscussed with respect to step 505. The layer 465 is a dielectric layerin some embodiments.

At step 610, the wafer 260 is transferred to the process chamber 420. Inthe process chamber 420, the back side 267 of the wafer 260 is supportedon the multi-zone chuck 300 having a plurality of zones Z1, Z2, . . . Znwith controllable clamping forces F1, F2, . . . Fn. The wafer 260 isthen secured to the multi-zone chuck 300 by controlling the clampingforces F1, F2, . . . Fn in the corresponding zones Z1, Z2, . . . Zn inaccordance with measured values T1, T2, . . . Tn of the thickness of thelayer 465 in the zones Z1, Z2, . . . Zn. In addition, the clampingforces F1, F2, . . . Fn are also controlled in accordance with measuredor calculated values W1, W2, . . . Wn of the wafer warpage in the zonesZ1, Z2, . . . Zn. The controlling operation is performed by thecontroller 440 which obtains the measured or calculated values P1, P2, .. . Pn, and W1, W2, . . . Wn from the corresponding metrologychamber(s), and which reads a first pre-stored data set 482, e.g., alook-up table (LUT), in the storage device 480.

In some embodiments, the controller 440 first calculates or extractsfrom the first pre-stored data set 482 and for each zone of themulti-zone chuck 300, a clamping force to compensate for the waferwarpage in the zone. For example, a clamping force to be generated in azone Z1 with a higher measured value W1 of wafer warpage (i.e., with alarge gap size between the back side 267 of the wafer 260 and themulti-zone chuck 300) is controlled to be higher than in another zone Z2with a lower measured value W2 of wafer warpage. The calculated orextracted clamping forces are presented in an initial set of voltagesV1, V2, . . . Vn to be applied to the corresponding electrodes in thecorresponding zones Z1, Z2, . . . Zn. The initial set of voltages V1,V2, . . . Vn would result in a uniform gap size across the wafer 260,because the corresponding clamping forces F1, F2, . . . Fn wouldeffectively flatten the wafer 260 and compensates for the wafer warpage.However, the presence of the layer 465 with a non-uniform thickness onthe back side 267 of the wafer 260 affects the clamping forces F1, F2, .. . Fn differently in zones with different values of the thickness ofthe layer 465. The gap size is, therefore, not uniform across the wafer.

The controller 440 further compensates for the non-uniformity in thethickness of the layer 465 by modifying the initial set of voltages V1,V2, . . . Vn based on the first pre-stored data set 482, in a mannersimilar to step 505. For example, the voltage V2, which would compensatefor the wafer warpage in the zone Z2 but for the thicknessnon-uniformity of the layer 465, is further increased to compensate fora high measured value of the thickness T2 of the layer 465 in the zoneZ2. Contrarily, the voltage V1, which would compensate for the waferwarpage in the zone Z1 but for the thickness non-uniformity of the layer465, is further reduced to compensate for a low measured value of thethickness T1 of the layer 465 in the zone Z1. As a result, a modifiedset of voltages V1, V2, . . . Vn is obtained. In some embodiments, notevery voltage in the initial set of voltage is adjusted. In someembodiments, the modified set of voltages V1, V2 . . . Vn is stored asvoltage data 483 in the storage device 480 for subsequent use on otherwafers in a wafer batch.

The first pre-stored data set 482 is determined in the manner describedwith respect to step 505, e.g., to tune the controlled clamping forcesF1, F2, . . . Fn toward a predetermined target which, in someembodiments, is a uniform heat transfer from the multi-zone chuck 300 tothe wafer 260 during a treatment to be performed on the wafer 260 in theprocess chamber 420.

In some embodiments, the controller 440 is configured to performAdvanced Process Control (APC). The control action of the controller 440in steps 603, 605, 610 is a feed-forward control to adjust the currenttreatment to be performed in the process chamber 420 in order tocompensate for a variability caused by an upstream treatment 419. Insome embodiments, the feed-forward control is wafer-to-wafer, orbatch-to-batch. In some embodiments, the controller 440 further includesa feed-back control to minimize a variability of the current treatmentin a subsequent run.

Specifically, after step 615 at which the current treatment is performedin the process chamber 420 on the wafer 260, subsequent steps 620, 625,630 constitute the feed-back control are performed. In some embodiments,steps 615-630 are similar to corresponding steps 515-530.

Steps may be added, replaced, changed order, and/or eliminated asappropriate, in accordance with the spirit and scope of embodiments ofthe disclosure. Embodiments that combine different features and/ordifferent embodiments are within scope of the disclosure and will beapparent to those skilled in the art after reviewing this disclosure.

One or more of the controllers 140, 230, 330, 440 is realized in someembodiments as a computer system 700 of FIG. 7. The system 700 comprisesa processor 701, a memory 702, a network interface (I/F) 706, a storage310, an input/output (I/O) device 708, and one or more hardwarecomponents 718 communicatively coupled via a bus 704 or otherinterconnection communication mechanism.

The memory 702 comprises, in some embodiments, a random access memory(RAM) and/or other dynamic storage device and/or read only memory (ROM)and/or other static storage device, coupled to the bus 704 for storingdata and instructions to be executed by the processor 701, e.g., kernel714, userspace 716, portions of the kernel and/or the userspace, andcomponents thereof. The memory 702 is also used, in some embodiments,for storing temporary variables or other intermediate information duringexecution of instructions to be executed by the processor 701.

In some embodiments, a storage device 710, such as a magnetic disk oroptical disk, is coupled to the bus 704 for storing data and/orinstructions, e.g., kernel 714, userspace 716, etc. The I/O device 708comprises an input device, an output device and/or a combinedinput/output device for enabling user interaction with the system 700.An input device comprises, for example, a keyboard, keypad, mouse,trackball, trackpad, and/or cursor direction keys for communicatinginformation and commands to the processor 701. An output devicecomprises, for example, a display, a printer, a voice synthesizer, etc.for communicating information to a user.

In some embodiments, the processes or functionality described withrespect to one or more of the controllers 140, 230, 330, 440 arerealized by a processor, e.g., the processor 701, which is programmedfor performing such processes. One or more of the memory 702, the I/F706, the storage 310, the I/O device 708, the hardware components 718,and the bus 704 is/are operable to receive design rules and/or otherparameters for processing by the processor 701. One or more of thememory 702, the I/F 706, the storage 310, the I/O device 708, thehardware components 718, and the bus 704 is/are operable to output theconfiguration with the optimal property as selected by the processor 701at steps 505, 605.

In some embodiments, one or more of the processes or functionalityis/are performed by specifically configured hardware (e.g., by one ormore application specific integrated circuits or ASIC(s)) which is/areincluded) separate from or in lieu of the processor. Some embodimentsincorporate more than one of the described processes in a single ASIC.

In some embodiments, the processes are realized as functions of aprogram stored in a non-transitory computer readable recording medium.Examples of a non-transitory computer readable recording medium include,but are not limited to, external/removable and/or internal/built-instorage or memory unit, e.g., one or more of an optical disk, such as aDVD, a magnetic disk, such as a hard disk, a semiconductor memory, suchas a ROM, a RAM, a memory card, and the like.

One or more of the following effects are achievable in accordance withone or more of the disclosed embodiments. A multi-zone chuck withcontrollable clamping forces include various adjustment capability,e.g., before or after a treatment. By appropriately controlling theclamping forces in the multiple zones of the multi-zone chuck, improvedchuck-wafer thermal conductivity uniformity is obtainable. The controlof clamping forces also compensates for a non-uniform thickness of alayer, e.g., a dielectric layer, on the back side of the wafer whichreduces defects such as chucking-induced particle defects or scraps dueto overstress. A film thickness uniformity tuning node is included inthe form of an APC controller which varies clamping forces of themulti-zone chuck, based on feed-forward and/or feed-back control, toachieve a uniform chuck-wafer heat transfer, and hence, a thicknessuniformity of a film being formed or treated on the wafer. The techniqueis applicable to both electrostatic and vacuum chucks.

According to some embodiments, a wafer processing system comprises atleast one metrology chamber, a process chamber, and a controller. The atleast one metrology chamber is configured to measure a thickness of afirst layer on a back side of a wafer. The process chamber is configuredto perform a treatment on a front side of the wafer. The front side isopposite the back side. The process chamber includes therein amulti-zone chuck. The multi-zone chuck is configured to support the backside of the wafer. The multi-zone chuck has a plurality of zones withcontrollable clamping forces for securing the wafer to the multi-zonechuck. The controller is coupled to the metrology chamber and themulti-zone chuck. The controller is configured to control the clampingforces in the corresponding zones in accordance with measured values ofthe thickness of the first layer in the corresponding zones.

According to some embodiments, a wafer processing system comprises atleast one metrology chamber, a multi-zone electrostatic chuck, and acontroller. The at least one metrology chamber is configured to measurewarpage of a wafer and a thickness of a dielectric layer on a back sideof the wafer. The multi-zone electrostatic chuck is configured tosupport the back side of the wafer. The multi-zone electrostatic chuckhas a plurality of zones with controllable clamping forces for securingthe wafer to the multi-zone electrostatic chuck. The controller iscoupled to the metrology chamber and the multi-zone electrostatic chuck.The controller is configured to control the clamping forces in thecorresponding zones in accordance with measured values of the warpageand the thickness of the dielectric layer in the corresponding zones.

According to some embodiments, a wafer processing system comprises atleast one metrology chamber, a process chamber, and a controller. The atleast one metrology chamber is configured to measure a first property ona back side of the wafer. The first property is different from warpageof the wafer. The process chamber is configured to perform a treatmenton a front side of the wafer. The front side is opposite the back side.The process chamber includes therein a multi-zone chuck. The multi-zonechuck is configured to support the back side of the wafer. Themulti-zone chuck has a plurality of zones with controllable clampingforces for securing the wafer to the multi-zone chuck. The controller iscoupled to the metrology chamber and the multi-zone chuck. Thecontroller is configured to control the clamping forces in thecorresponding zones in accordance with measured values of the firstproperty in the corresponding zones.

It will be readily seen by one of ordinary skill in the art that one ormore of the disclosed embodiments fulfill one or more of the advantagesset forth above. After reading the foregoing specification, one ofordinary skill will be able to affect various changes, substitutions ofequivalents and various other embodiments as broadly disclosed herein.It is therefore intended that the protection granted hereon be limitedonly by the definition contained in the appended claims and equivalentsthereof.

What is claimed is:
 1. A wafer processing system, comprising: at leastone metrology chamber configured to measure a thickness of a first layeron a back side of a wafer; a storage device; a process chamberconfigured to perform a treatment on a front side of the wafer, thefront side opposite the back side, the process chamber including thereina multi-zone chuck, the multi-zone chuck configured to support the backside of the wafer, the multi-zone chuck having a plurality of zones withcontrollable clamping forces for securing the wafer to the multi-zonechuck; and a controller communicatively coupled to the at least onemetrology chamber, the storage device, and the multi-zone chuck, thecontroller being configured to: obtain, from the at least one metrologychamber, a plurality of measurement values of the thickness of the firstlayer, each measurement value of the plurality of measurement valuescorresponding to a zone of the plurality of zones, extract acorresponding clamping force value from a data set stored in the storagedevice, for the each measurement value of the plurality of measurementvalues, and control the clamping forces in the zones of the plurality ofzones of the multi-zone chuck in accordance with the correspondingclamping force values.
 2. The wafer processing system of claim 1,further comprising: at least one heater included in the multi-zone chuckand configured to heat the wafer secured on the multi-zone chuck,wherein the controller is configured to control the clamping forces inthe zones of the plurality of zones of the multi-zone chuck to achieve auniform heat transfer from the multi-zone chuck to the wafer.
 3. Thewafer processing system of claim 1, wherein the controller is configuredto control the clamping forces to compensate for a non-uniformity in thethickness of the first layer.
 4. The wafer processing system of claim 1,wherein the at least one metrology chamber is configured to measure aproperty of the wafer after the treatment, the property being differentfrom the thickness of the first layer, and the controller is configuredto adjust the clamping forces in one or more zones of the plurality ofzones of the multi-zone chuck in accordance with measured values of theproperty in the corresponding zones.
 5. The wafer processing system ofclaim 4, wherein the controller is configured to cause the multi-zonechuck to secure a subsequent wafer with the adjusted clamping forces inthe corresponding zones of the plurality of zones of the multi-zonechuck.
 6. The wafer processing system of claim 4, wherein the propertycomprises a thickness of a second layer on the front side of the wafer,and the controller is configured to adjust the clamping forces tocompensate for a non-uniformity in the thickness of the second layer. 7.The wafer processing system of claim 4, wherein the measured value ofthe property of the wafer in a first zone is greater than that in asecond zone among the plurality of zones of the multi-zone chuck, andthe controller is configured to adjust the clamping forces by at leastone of (i) reducing the clamping force in the first zone or (ii)increasing the clamping force in the second zone.
 8. The waferprocessing system of claim 1, wherein the multi-zone chuck is anelectrostatic chuck having a plurality of electrodes, each zone of theplurality of zones of the multi-zone chuck includes at least oneelectrode of the plurality of electrodes, and the controller isconfigured to control the clamping forces by causing different voltagesto be applied to the electrodes in different zones of the plurality ofzones of the multi-zone chuck in accordance with different measuredvalues of the thickness of the first layer in the corresponding zones ofthe plurality of zones of the multi-zone chuck.
 9. The wafer processingsystem of claim 1, wherein the multi-zone chuck is a vacuum chuck havinga plurality of vacuum ports, each zone of the plurality of zones of themulti-zone chuck includes at least one vacuum port of the plurality ofvacuum ports, and the controller is configured to control the clampingforces by causing different vacuum pressures to be applied to the vacuumports in different zones of the plurality of zones of the multi-zonechuck in accordance with different measured values of the thickness ofthe first layer in the corresponding zones of the plurality of zones ofthe multi-zone chuck.
 10. A wafer processing system, comprising: atleast one metrology chamber configured to measure warpage of a wafer anda thickness of a dielectric layer on a back side of the wafer; a storagedevice; a multi-zone electrostatic chuck configured to support the backside of the wafer, the multi-zone electrostatic chuck having a pluralityof zones with controllable clamping forces for securing the wafer to themulti-zone electrostatic chuck; and a controller communicatively coupledto the at least one metrology chamber, the storage device, and themulti-zone electrostatic chuck, the controller being configured to:obtain, from the at least one metrology chamber, a plurality of firstmeasurement values of the warpage of the wafer, each first measurementvalue of the plurality of first measurement values corresponding to arespective zone of the plurality of zones, obtain, from the at least onemetrology chamber, a plurality of second measurement values of thethickness of the dielectric layer, each second measurement value of theplurality of second measurement values corresponding to a respectivezone of the plurality of zones, extract from a data set stored in thestorage device, a plurality of clamping force values corresponding tothe plurality of zones, the plurality of clamping force values beingbased on at least one first measurement value of the plurality of firstmeasurement values and at least one second measurement value of theplurality of second measurement values, and control the clamping forcesin the zones of the plurality of zones of the multi-zone electrostaticchuck in accordance with the corresponding clamping force values. 11.The wafer processing system of claim 10, further comprising: at leastone heater included in the multi-zone electrostatic chuck and configuredto heat the wafer secured on the multi-zone electrostatic chuck, whereinthe controller is configured to control the clamping forces in the zonesof the multi-zone electrostatic chuck to achieve a uniform heat transferfrom the multi-zone electrostatic chuck to the wafer.
 12. The waferprocessing system of claim 10, wherein the multi-zone electrostaticchuck has a plurality of electrodes, each zone of the plurality of zonesof the multi-zone electrostatic chuck includes at least one electrode ofthe plurality of electrodes, and the controller is configured to controlthe clamping forces by determining a set of voltages to be applied tothe plurality of electrodes, wherein the voltage of the set of voltagesto be applied to the electrode of the plurality of electrodes in a zoneof the plurality of zones with a higher first measurement value of theplurality of first measurement values is higher than the voltage of theset of voltages to be applied to the electrode of the plurality ofelectrodes in a zone of the plurality of zones with a lower firstmeasurement value of the plurality of first measurement values.
 13. Thewafer processing system of claim 12, wherein the controller isconfigured to control the clamping forces further by: modifying thedetermined set of voltages by at least one of (i) increasing the voltageof the set of voltages to be applied to the electrode of the pluralityof electrodes in a zone with a higher second measurement value of theplurality of second measurement values, or (ii) decreasing the voltageof the set of voltages to be applied to the electrode of the pluralityof electrodes in a zone with a lower second measurement value of theplurality of second measurement values, and applying the voltages in themodified set of voltages to the corresponding electrodes in theplurality of zones of the multi-zone electrostatic chuck.
 14. The waferprocessing system of claim 13, further comprising: a process chamberincluding the multi-zone electrostatic chuck therein, the processchamber configured to deposit a layer on the front side of the waferwhile the wafer is being secured by the controlled clamping forces ofthe multi-zone electrostatic chuck, wherein the at least one metrologychamber is configured to measure a thickness of the deposited layer onthe front side of the wafer, and the controller is configured to adjustthe modified set of voltages in accordance with measured values of thethickness of the deposited layer in the corresponding zones.
 15. Thewafer processing system of claim 14, wherein the controller isconfigured to adjust the modified set of voltages by at least one of (i)increasing the voltage of the set of voltages to be applied to theelectrode of the plurality of electrodes in a zone of the plurality ofzones with a lower measured value of the thickness of the depositedlayer, or (ii) decreasing the voltage of the set of voltages to beapplied to the electrode of the plurality of electrodes in a zone of theplurality of zones with a higher measured value of the thickness of thedeposited layer.
 16. The wafer processing system of claim 15, whereinthe controller is configured to cause the modified set of voltages to beapplied to the corresponding electrodes in the plurality of zones of themulti-zone electrostatic chuck to secure a subsequent wafer on themulti-zone electrostatic chuck.
 17. A wafer processing system,comprising: at least one metrology chamber configured to measure a firstproperty on a back side of the wafer, the first property being differentfrom warpage of the wafer; a storage device; a process chamberconfigured to perform a treatment on a front side of the wafer, thefront side opposite the back side, the process chamber including thereina multi-zone chuck, the multi-zone chuck configured to support the backside of the wafer, the multi-zone chuck having a plurality of zones withcontrollable clamping forces for securing the wafer to the multi-zonechuck; and a controller communicatively coupled to the at least onemetrology chamber, the storage device, and the multi-zone chuck, thecontroller being configured to: obtain, from the at least one metrologychamber, a plurality of measurement values of the first property, eachmeasurement value of the plurality of measurement values correspondingto a zone of the plurality of zones, extract a corresponding clampingforce value from a data set stored in the storage device, for the eachmeasurement value of the plurality of measurement values, and controlthe clamping forces in the zones of the plurality of zones of themulti-zone chuck in accordance with the corresponding clamping forcevalues.
 18. The wafer processing system of claim 17, wherein thecontroller is configured to perform an Advanced Process Control (APC)technique using a feed-forward arrangement to control the clampingforces in the corresponding zones of the multi-zone chuck.
 19. The waferprocessing system of claim 17, further comprising at least one heaterincluded in the multi-zone chuck and configured to heat the wafer viaheat transfer from the multi-zone chuck to the wafer, wherein thecontroller is configured to perform an Advanced Process Control (APC)technique using a feed-forward arrangement to control the clampingforces in the corresponding zones of the multi-zone chuck to compensatefor a non-uniformity in the heat transfer.
 20. The wafer processingsystem of claim 17, wherein the plurality of zones in the multi-zonechuck is arranged in at least one of (i) a ring form or (ii) a gridform.